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Plant Profiles

Today in the Garden of a Lifetime: Empress Tree Rebounding

Empress tree is a large self-seeding weed tree in Zone 7 and warmer; in Zone 5, a non-flowering die-back shrub. Here in warm Zone 6, the quirks of each Winter move a given tree's performance to a new spot on that spectrum.

Will a given Winter be mild enough for that year's new growth to survive? Will the next Summer be long and hot enough to allow those stems to form buds that Fall—or will another year of growth be needed? After buds are finally formed one Fall or the next, will the coming Winter be mild enough for them to mature to flowers the following Spring?

My penchant for pollarding adds still more suspense. At the minimum, it's three years from pollarding to flowering: pollarding the first Spring, forming buds the second Fall, flowering the third Spring and then pollarding again. Alas, the ultra-eager new wood that pollarding encourages seems to be less hardy than free-range growth and so, therefore, are the buds it forms.

See the bare branches poking up through new shoots from lower down? The Winter of 2015-16 killed back to the trunk the branches formed by a Spring 2015 pollarding. Just as frustrating, the Winter of 2014-15 killed the flowerbuds that had finally been formed after a pollarding of 2012, which is why I pollarded in 2015.

OK, fine. I cut off the dead stems, and the new shoots will take over.

In this location, in this climate, a pollarded Paulownia tomentosa teaches patience as well as humility—and a commitment to many years of healthy living. How often will the three- or even four-year cycle of pollarding to flowering coincide with a stretch of mild-enough Winters? Once a decade?

Here's hoping that the Winter of 2016-17 will permit this year's growth to survive. Then perhaps buds could be formed in Fall of 2017 or, without fail, Fall of 2018. If the following Winter is benign, those buds could survive so that flowering could occur in Spring 2018 or 2019. Right after flowering is through, I could then pollard and begin the cycle again. You'll know the progress phase by phase, year by year.

Exceptional Winter dieback wasn't the only surprise of 2016. Infestations of winter moth and gypsy moth caterpillars were the worst in decades, leaving many oaks, roses, and fruit trees completely defoliated. They'll grow new leaves, but it's a setback for overall vigor and, of course, a horrifying process to watch.

The trees that caterpillars avoid were striking in their full greenery. You'd think that the enormous and fast-forming paulownia foliage would be juicy and delicious. But as you can see in the picture below, it's caterpillar-free.

Catalpa foliage is nearly as lush and large—look at the leaves of the variegated as well as purple forms I grow—and yet it, too, has been avoided. Linden foliage is safe, as well.

No, there isn't something magical about heart-shaped leaves; my wisterias are 'pillar free, too. But the same cold that killed my paulownia stems also killed the wisteria buds. I have plenty of green growth, but it was the first Spring in memory without wisteria flowers.

One way and another, the whims of Nature easily trump the efforts of Man.

Here's the link to all the posts on Paulownia tomentosa: The pollarded tree with its claw-like bare branches grasping the sky in Winter, the tree in lush leaf in Summer, the speculation on how much time the stems of a pollarded-in-Spring-2012 empress tree would need to form buds and flowers, and the buds that had developed by Fall 2014.